Phrase used interchangeably with glasscock. In 2006 a whale got lost and swam up the thames estuary. During those few days, the b3ta board was awash with not only humourous posts about it, but also people just posting threadwastes about it, so it became a bit tiresome. The event was so ubiquitous that it reminded boarders of the coverage of John Peel's death two years previously. So much so, that often the phrase now used is "John Peel's in the thames?!"
Origin: http://www.b3ta.com/talk/1160843